Lets start from bottom! As far as where your thecal sac
ends and conus terminates, there is nothing to worry because it is normal. You seem to have disc wear and tear at multiple levels. As far as the scan is concerned, the worse level is at the L4/5 and L5/S1 levels. However, the symptoms you describe cannot be explained by the T11/12 or Lower lumbar disc bulges. your symptoms should settle with simple pain killers. As far as your back is concerned, it may be useful to keep it fit and you can consider swimming or another appropriate back strengthening exercise program.
Hope this helps!